The recent finding that eukaryotic chromatin consists of discrete DNA-histone subunits, the 'nu' bodies or nucleosomes, has provided a valuable framework for examining other features of chromatin structure, function, and assembly. We propose to continue our work on the structure of the eukaryotic genome using high resolution electron microscopy as the primary tool, and have designed experiments to answer specific questions in the areas of chromatin reconstitution, the structural and antigenic roles of non-histone chromosomal proteins (NHCPs), chromatin replication, and nucleosome packaging.